Selenium and mercury in native and introduced fish species of patagonian lakes, Argentina.

A survey of mercury (Hg) and selenium (Se) contents was performed in fish collected from lakes located in two National Parks of the northern patagonian Andean range. Two native species, catfish (Diplomystes viedmensis) and creole perch (Percichthys trucha), and three introduced species, brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss), and brook trout (Salvelinus fontinalis), were caught from lakes Nahuel Huapi, Moreno, Traful, Espejo Chico, and Guillelmo belonging to Nahuel Huapi National Park and from lakes Futalaufquen and Rivadavia, Los Alerces National Park. In lake Moreno, fish diet items were analyzed and rainbow trout grown in a farm. Hg and Se were measured in muscle and liver tissues by instrumental neutron activation analysis. The average concentrations in muscle of Hg for all species, ages, and lakes are between 0.4 to 1.0 microg g(-1) dry weight (DW) with a few fish, mainly native, exceeding the United States Environmental Protection Agency health advisory for freshwater fish limited consumption, and from 0.8 to 1.5 microg g(-1) DW for Se. Average concentrations in liver of Hg in all species range from 0.4 to 0.9 microg g(-1) DW. Brown trout, the top predator in these lakes, showed the lowest average Hg burden in both tissues. Se concentrations in the liver of brown and rainbow trout, up to 279 microg g(-1) DW, are higher than those expected for nearly pristine lakes, exceeding 20 microg g(-1) DW, the threshold concentration associated with Se toxicity. These species show lower Hg contents in muscle, suggesting a possible detoxification of Hg by a Se-rich diet. Creole perch and velvet catfish livers have lower Se concentrations, with a narrower span of values (2.3 to 8.5 microg g(-1) and 3.3 to 5.5 microg g(-1) DW respectively).

Trace elements as fingerprint of lake of Provenance and of species of some native and exotic fish of northern Patagonian lakes.

A survey of trace element contents in fish muscle and liver was performed in different lakes of two northern Patagonian national parks: Nahuel Huapi and Los Alerces national parks. The aim of the work was to obtain the first set of reference data on elements that are not liable to be disturbed by human activities and to identify compositional patterns related to the species and site of collection. The species studied are native creole perch and velvet catfish and exotic brown trout, rainbow trout, and brook trout. The elements analyzed are Br, Cs, Fe, Rb, Se, Na, and Zn. Trace elements in muscle of brown trout, rainbow trout, and creole perch showed statistical patterns that allow one to identify the national park of origin, as well as which of the lakes (Traful, Espejo Chico, or the Nahuel Huapi-Moreno system) of the Nahuel Huapi National Park from which they come. Contents in the liver provide similar but less clear patterns than contents in muscle; however, in some particular cases, they provide additional information. Trace element contents in muscle are also good indicators of the species collected within a lake.

Rb-Cs ratio as an indicator of fish diet in lakes of the Patagonia, Argentina.

The ratios of Rb to Cs contents were studied in five fish species from seven lakes located in the Patagonia Andean Range, Argentina in order to trace fish diet. The species studied were native velvet catfish (Diplomistes viedmensis) and creole perch (Percichthys trucha), and exotic brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss), and brook trout (Salvenilus fontinalis). Rainbow trout specimens from two farms were also studied, as well as fish food items and native mussels (Diplodon chilensis). Rb and Cs concentrations were determined by instrumental neutron activation analysis. A positive correlation of Cs concentration in the muscle of velvet catfish with fish length was observed, probably associated with the long biological half-life of this element in this species, whereas the Rb concentration remained constant, hence inhibiting the use of Rb-Cs ratios as a tracer in this case. Seasonal variations observed for rainbow trout and Cs concentration background bias in one of the lakes studied are also a limiting factor to the use of Rb-Cs ratios as a diet tracer. Rb-Cs ratios allowed clear differentiation of rainbow trout raised in farms from the natural specimens that lived in the same environment, in agreement with Rb-Cs ratios determined in both diets. Rb-Cs ratios in rainbow trout showed significant differences between Rivadavia and Futalaufquen lakes compared to Moreno and Nahuel Huapi lakes, which could be associated with a higher participation of plankton in the diet in the first case. No relevant variations in Rb-Cs ratios of brown trout were observed, probably because of the similarity in the diet.

Bilateral motor cortex output with intended unimanual contraction in congenital mirror movements.

In congenital mirror movements (MM), it is unclear whether the "mirror" motor cortex (M1) produces output during intended unimanual movements. In two patients with MM, the cortical silent period (CSP) was abnormally short after focal transcranial magnetic stimulation (TMS) of either M1, but simultaneous bilateral TMS led to significant CSP lengthening. Thus, it is likely that the shortened CSP after unilateral TMS is caused by output from the nonstimulated M1, suggesting that both M1 produce output with intended unimanual movements in patients with MM.

Neurophysiologic exploration: a reliable tool in HIV-1 encephalopathy diagnosis in children.

BACKGROUND: HIV-1 related encephalopathy has a bad prognostic meaning in the course of AIDS disease, but the early association of different drugs can modify its course. For this reason it is very important to recognize CNS involvement as soon as possible. As shown in the literature, at least in adult studies, EEG and Evoked Potentials (EP) are good tools in evaluating CNS alterations. In children data are rare. METHODS: A ten-year prospective study of 44 infected children out of 142 born from HIV-1 positive mothers has been done. The children have been submitted to EEG recording every six months in the first 18 months of life and then every year, to multimodal EP every six months. A total of 357 EEG, 47 P-VEP, 62 F-VEP and 98 BAEP have been performed. RESULTS: EEG: we found no pathologic results in patients belonging to category A; results were pathologic in 17.7% in category B, in 47.7% in C and in 77% of encephalopathic patients. It seems that EEG alterations are parallel to disease progression, with a relative risk of developing encephalopathy (R.R. = 1.15) and of death (R.R. = 2.33) for patients belonging to category C. We obtained a statistically significant lengthening in BAEP interpeak latency of left ear in all groups. For patients in category C the risk of developing encephalopathy is statistically significant (p = 0.045; R.R. = 6.75) and risk of death is high (R.R. = 4). CONCLUSIONS: Neurophysiologic exams are a reliable tool for the diagnosis of encephalopathy, in addition to clinical evidence.

Evolution of HIV-1 encephalopathy in children.

BACKGROUND: This study has been conducted on a series of HIV-1 infected children, with the aim of illustrating the features of encephalopathy onset, its evolution and its influence on life expectancy. The most useful exams for diagnosis are also outlined. METHODS: The perspective study lasted from January 1989 to June 1997. Forty six symptomatic patients, out of 142 seropositive children, were followed up in the Department of Paediatric and Adolescence Sciences of the University of Turin. The patients, now between 1 yr 2 mth and 13 yr 9 mth old, were born from HIV-1 seropositive mothers; seroreverters have been excluded. Scheduled neuropsychiatric consultations were used, consisting of a neurologic exam and an interview with parents, cognitive evaluations, EEGs, Evoked Potentials and CT scans. The results have been evaluated with log-rank test for the analysis of the survival curves. RESULTS: We found a significantly higher mortality rate in encephalopathic versus non encephalopathic patients; encephalopathic patients, in whom neurologic signs began in the first year of life, have a worse prognosis than the other patients, in whom encephalopathy appeared later. We did not find a statistical correlation between clinical course and immunological deficit. The clinical features of encephalopathy are mainly characterized by pyramidal signs and cognitive deterioration. Clinical sign evolution is linked to the age of encephalopathy onset: plateau pattern encephalopathy, characterized by an early onset, severe motor signs and cognitive delay from the very beginning, shows a greater severity and a shorter survival than progressive encephalopathy, characterized by a slowly progressive evolution of pyramidal signs, to which a cognitive deterioration may be added. CONCLUSIONS: Neuropsychological exams can be helpful in the diagnosis and follow-up of encephalopathy.

[Contribution of ambulatory EEG recording (Medilog 9000) in a population of epileptics]. / Apport de l'enregistrement EEG ambulatoire (Medilog 9000) dans une population d'épileptiques.

Thirty-four epileptic patients, aged 9 to 36, were submitted to A/EEG between May 1987 and July 1988. All patients had a thorough clinical and EEG work-up including long-term conventional EEG, afternoon polygraphic sleep recording and, in some cases, full-night EEG and video monitoring. Patients were divided into 2 groups: group I included 19 patients (18 with symptomatic partial epilepsy (SPE) and 1 with idiopathic generalized epilepsy (IGE) in whom no seizure had ever been recorded in spite of EEG recordings averaging a total of 16 hrs 10 min, awake and asleep); group II included 15 subjects (6 with SPE, 5 with IGE, 3 with symptomatic GE and 1 with undetermined epilepsy) in whom one or several seizures had been recorded. A/EEG was performed in order to: 1) obtain better clinical and EEG characterization of seizures, 2) study the circadian distribution of seizures, 3) verify the efficacy of drug treatment and, 4) establish the epileptic or non-epileptic nature of some ictal events. The results of A/EEG were considered positive in 52.63% of group I patients and in 93.33% of group II patients. The authors discuss the specific advantages of A/EEG vs conventional EEG: recording of seizures with random occurrence, of seizures accompanied by falls, checking the remission of seizures.

EEG diagnostic and predictive value on HIV infection in childhood.

This prospective study evaluated the electroencephalographic (EEG) diagnostic and prognostic value in childhood HIV infection. It was carried out on 125 subjects and included all Piemonte's seropositive children. The EEG was repeated every three months during the first 15 months of life, and then, at least, annually in the P1 and P2 group. Data of group P2 was compared blindly to that of the seroconverted control group of the same age and risk. EEG results were normal in P0, P1 and control patients. In group P2, EEG was abnormal in 35.5% of subjects, of these 54.6% developed an encephalopathy with a delay of 2.5 months to 2 years 11 months. EEG is therefore useful to evaluate early CNS damage and to identify onset features and evolution of encephalopathy in P2 patients.

Diagnostic value of multimodal evoked potentials in HIV-1 infected children.

Evoked potentials (EP) help guide the diagnosis of central nervous system involvement in demyelinating pathologies regarding both children and adults, and in human immunodeficiency virus-1 (HIV-1) correlated pathologies only in regard to adult patients. EP have been shown to be useful in highlighting early signs of the disease. We therefore studied EP in HIV-1 infected children with the aim of verifying the association of results with disease progression, clinical signs and electroencephalogram, and individualizing the most reliable test. Thirty-six patients (20 male and 16 female subjects, age range: 10 months to 12 years) belonging to a group of 45 symptomatic subjects seen at the Pediatric Department were included into the study from November 1991 to December 1994. Ten presented with neurological signs as of disease onset, eight others developed encephalopathy during the follow-up. One hundred seventeen EP, i.e., 27 pattern visual, 64 flash visual and 26 brain stem auditory EP, were recorded. Univariate statistical analysis using the Wilcoxon-Mann-Whitney U test and Student's t test was done. As a whole, we found 22.5% of abnormal EP in subjects without neurological signs and 28.3% in subjects with neurological signs. Results that were obtained suggested a close relationship between both the pattern of visual and brain stem auditory EP exams and disease progression.

Heavy metal and other trace elements in native mussel Diplodon chilensis from Northern Patagonia Lakes, Argentina.

Native mussels, Diplodon chilensis, were sampled from four lakes in Nahuel Huapi National Park, Northern Patagonia, Argentina in order to evaluate heavy-metal distribution in the region and to assess the contribution of this compartment of the trophic web to their circulation in the food chain. The concentration of potential pollutants Ag, As, Cr, Hg, Sb, and Se, and other nine elements of interest (Ba, Br, Ca, Co, Cs, Fe, Na, Sr, and Zn) were determined in Diplodon chilensis pooled samples. Digestive glands were analyzed separately from soft tissues. Geological tracers Sc, Ta, Th, and rare earth elements were also determined in order to discriminate lithophile contributions. Elemental concentrations of Ba, Br, Fe, Sr, Se, and Zn in total soft tissues samples do not show significant differences among sampling sites. Arsenic and Cr contents in total soft tissues and digestive gland pooled samples are higher in sampling points close to zones with human settlements. Silver contents in samples collected in Lake Nahuel Huapi were higher than in the other lakes studied, and up to 50-fold higher than the sample collected in Lake Traful, considered as the reference. Mercury highest concentration values measured in total soft tissues pooled samples from lakes Nahuel Huapi and Moreno were found to be similar to those observed in other reported Hg contamination situations, and they are three to five times higher than those of the reference samples collected in Lake Traful.

Semi-late onset and rapidly progressive case of Lafora's disease with predominant cognitive symptoms.

The authors report a sporadic case of Lafora's disease, unusual for the comparatively late age at onset and atypical evolution. Discrete visual phenomena that may be considered as partial seizures occurred at age 19 years. A generalized tonic-clonic seizure occurred at 20 years of age and myoclonus became apparent a few weeks later. A massive cognitive dysfunction was clearly apparent 3 months after the first seizure and further mental deterioration occurred although seizures were controlled by medication and myoclonus remained minimal. The EEG showed the typical association of generalized and focal (occipital) changes. Axillary++ skin and muscle biopsies were positive and easily confirmed the diagnosis. The clinical presentation of Lafora's disease is considered by the authors to be sufficient for a clinical diagnosis, even in such an atypical case. Confirmation by skin biopsy is easily obtainable.

Surgery for drug resistant partial epilepsy in children with focal cortical dysplasia: anatomical-clinical correlations and neurophysiological data in 10 patients.

OBJECTIVE: To analyse a population of children with focal cortical dysplasia operated on for drug resistant partial epilepsy, with emphasis on clinical features, seizure semiology, interictal and ictal EEG and stereo EEG findings, histological and topographical characteristics of the lesions, extension and localisation of cerebral excision, and its postoperative effect on seizure frequency. METHODS: 10 patients were studied, aged between 26 months and 11 years (median 6 years). Magnetic resonance imaging (MRI) abnormalities were unilobar (temporal 3, frontal 2), bilobar (2), or multilobar (1); the two patients with negative MRI suffered from frontal seizures. Presurgical diagnostic steps varied in complexity and invasiveness depending on the anatomical/electrical/clinical features of each patient. In four patients they included only scalp video EEG monitoring, and in six, also invasive recordings using stereotactically implanted intracerebral electrodes. Surgery consisted of corticectomy plus lesionectomy in all cases. RESULTS: 70% of the patients were seizure-free after a minimum postoperative follow up of 25 months. These included three patients with temporal lesions and four of seven patients with other lobar or multilobar extratemporal localisation. One patient had improvement in seizure control. Outcome was poor in multilobar patients, but a class Ia outcome was obtained in one case after partial lesionectomy associated with bilobar corticectomy. All patients showed developmental improvement. CONCLUSIONS: Analysis of the data in these patients allowed the production of an "anatomical-clinical concordance" list, which appeared to be correlated with the diagnostic steps performed. Carrying out a stereo EEG exploration in the most complex cases proved useful in defining the epileptogenic zone in extratemporal and multilobar epilepsies. Stereo EEG recordings facilitated a tailored resection of extralesional cortex.

Early-onset benign occipital seizure susceptibility syndrome.

PURPOSE: Childhood epilepsy with occipital paroxysms (CEOP) is characterised by ictal visual hallucinations and occipital epileptiform activity on interictal EEG. A variant has been described with nonvisual symptoms including tonic head and eye deviation, vomiting, and episodes of partial status epilepticus. We fully documented the electroclinical features of such patients to determine whether classification separate from CEOP is justified. METHODS: This was a multicentre study with participating investigators submitting details of patients with idiopathic occipital seizures characterised by ictal head or eye deviation and vomiting. RESULTS: One hundred thirteen patients were recruited. Seizures began in early childhood (mean, 4.6 years) and occurred infrequently (mean total seizures, 3); 30% of patients had only a single seizure. Two thirds of seizures were nocturnal. Ictal eye deviation occurred in 79%, vomiting in 70%, and head deviation in 35%. Seizures were predominantly complex partial in type. Partial status epilepticus occurred in 44% of patients. Seventy-four percent of patients had occipital interictal EEG epileptiform activity, predominantly right sided, with fixation-off sensitivity. Extraoccipital EEG abnormalities occurred in 35% of patients. Prognosis was excellent: the mean duration of active seizures was 1 year. CONCLUSIONS: Although the two groups shared identical EEG features, the distinct clinical symptoms probably justify separate classification. Early-onset benign occipital seizure syndrome (EBOSS) is suggested as an appropriate name for the variant group.

Water quality and fish surveys of Piedra del Aguila Reservoir 1993-1997

En este trabajo se presentan resultados del monitoreo bimestral que se realizó sobre la calidad del agua y los peces en el reservorio del Embalse Piedra del Aguila